Discusses causes and symptoms of food allergies. Covers what increases risk. Discusses treatment options, including medicine choices. Offers home care and prevention tips. Covers when to call a doctor.

Food Allergies

Topic Overview

Is this topic for you?

This topic has general
information about food allergies. If you would like more specific information
about peanut allergy, see the topic
Peanut Allergy.

What is a food allergy?

When you have a food
allergy, your body thinks certain foods are trying to harm you. Your body
fights back by setting off an
allergic reaction. In most cases, the symptoms are
mild—a rash or an upset stomach. A mild reaction is no fun, but
it isn't dangerous. A serious reaction can be deadly. But quick treatment can
stop a dangerous reaction.

Allergies tend to run in families. You
are more likely to have a food allergy if other people in your family have
allergies like hay fever, asthma, or eczema (atopic dermatitis).

Food allergies are more common in children
than in adults. Children sometimes outgrow their food
allergies, especially allergies to milk, eggs, or soy. But if you develop a food allergy as an adult, you will most likely
have it for life.

Food allergy versus food intolerance

Food intolerances are much more common than food allergies. True food allergies are a reaction to food or food additives by your body's immune system.

Many people think they have a food allergy, but in fact they have a food intolerance. Food intolerance is much more common.
It can cause some of the same symptoms as a mild food allergy, like an upset stomach. But a food intolerance does
not cause an allergic reaction. A food intolerance can make you feel bad, but it is not dangerous. A serious food
allergy can be dangerous.

What are the symptoms?

Food allergies can cause
many different symptoms. They can range from mild to serious. If you eat a food
you are allergic to:

Your mouth may tingle, and your lips may
swell as you start to eat the food.

You may have a stuffy nose,
wheeze, or be short of breath when the allergens reach your mouth and lungs.

You may have cramps, an upset stomach, or
diarrhea as the food is digested.

You may feel dizzy or lightheaded if your blood pressure drops as the allergens circulate through your bloodstream.

You may have itchy skin with red, raised bumps called
hives as the allergens reach your skin.

Kids usually have the same symptoms as adults. But
sometimes a small child just cries a lot, vomits, has diarrhea, or does not
grow as expected. If your child has these symptoms, see your doctor.

Some people have symptoms after eating even a tiny bit of a problem food.
As a rule, the sooner the reaction begins, the worse it will be.

The most severe reaction is called
anaphylaxis (say "ANN-uh-fuh-LAK-suss"). It affects
your whole body. Anaphylaxis can start within a few minutes to a few hours after you eat the
food. And the symptoms can go away and come back hours later. If you have
anaphylaxis:

Your throat and tongue may swell quickly.

You may suddenly start wheezing or have trouble
breathing.

You may feel sick to your stomach or vomit.

You may feel faint or pass out.

Anaphylaxis can be deadly. If you have (or see someone
having) any of these symptoms, call 911 right away.

What foods most often cause a food allergy?

A few
foods cause most allergies. The protein in a food that causes an allergy is called a food
allergen.

If you are allergic to one food, you may also be allergic
to other foods like it. So if you are allergic to shrimp, you may also be
allergic to lobster or crab.

How is a food allergy diagnosed?

Your doctor will
ask questions about your medical history and any family food allergies. And he
or she will do a physical exam. Your doctor will also ask what symptoms you
have. He or she may want you to write down everything you eat and any reactions
you have. Your doctor will consider other possibilities that could be confused with food allergies, such as a food intolerance.

Because food allergies can be confused with other problems, it is important for your doctor to do a test to confirm that you have a food allergy. Your doctor may first start out with either skin testing or a blood test to determine what you are allergic to. But an oral food challenge is the best way to diagnose a food allergy. In an oral food challenge, you will eat a variety of foods that may or may not cause an allergic reaction. Your doctor
watches to see if and when a reaction occurs.

A skin prick test can help to find out which foods will cause a reaction. The doctor will put a little bit of liquid
on your skin and then prick your skin. The liquid has some of the possible food
allergen in it. If your skin swells up like a mosquito bite, your doctor knows
that you are allergic to that food. Your doctor may also do blood tests to look for
the chemicals in your blood that cause an allergic reaction.

How is it treated?

The best treatment
is to never eat the foods you are allergic to. Learn to read food labels and
spot other names for problem foods. For example, milk may be listed as
"caseinate," wheat as "gluten," and peanuts as "hydrolyzed vegetable protein."
When you eat out or at other people's houses, ask about the foods you are
served.

If you have a history of severe food allergies, your
doctor will prescribe an allergy kit that contains
epinephrine (say "eh-puh-NEH-fren") and
antihistamines. An epinephrine shot can slow down or stop an allergic reaction.
Your doctor can teach you how to give yourself the shot.

You can
have symptoms again even after you give yourself a shot. So go to the emergency
room every time you have a severe reaction. You will need to be watched for
several hours after the reaction.

If you have had a serious
reaction in the past, your chance of having another one is high. Be
prepared.

Check the expiration dates on the medicines in your kit, and
replace the medicines as needed.

If your child has a food allergy, what else should you think about?

Talk to your child's teachers and caregivers. They should
know how to keep problem foods away from your child. Teach them what to do if
your child eats one of these foods by mistake.

If your child has
ever had a severe reaction, keep an allergy kit nearby at all times. Some kids
carry their kit in a fanny pack. Have your child wear a medical alert bracelet.
Teach all caregivers to act quickly. They should:

Cause

Food allergies
occur when the body's immune system overreacts to substances in food you have
eaten, triggering an
allergic reaction. Food allergies are more common in
young children than in adults.

Milk, eggs, peanuts, tree nuts, fish, shellfish, wheat, and soy cause
most problems in children. Some babies are so sensitive to these
foods that if the offending food is eaten by the mother, drinking her breast
milk can cause a reaction. Most children outgrow allergies to eggs, milk,
wheat, and soy.

Peanuts, tree
nuts, fish, and shellfish cause most of the allergic reactions in teens and
adults. Adults typically remain allergic to the food for life.

Food allergies are most common in people who are
atopic, meaning they have an inherited tendency to
have allergic conditions. These people are more likely to have asthma, various
allergies, and a skin condition called
atopic dermatitis. Asthma can make the reaction to a food more severe.

If you are highly
sensitive to a certain food, you may have an allergic reaction simply by
being near where the food was prepared or served.

Celiac disease
is an abnormal immune system reaction to gluten, a protein found in grains like wheat and rye. It damages the small intestine so that it can't do a good job of absorbing nutrients from your food. For more information, see the topic
Celiac Disease.

Cross-reactivity

Many people, but not all people, are allergic to foods
that are similar or somehow related. This is called cross-reactivity. For
example, if you are allergic to shrimp, you may also be allergic to other
shellfish, like crab or lobster. If you are allergic to peanuts, you may be
allergic to other members of the legume family, such as peas and beans. You don't need to stop eating a cross-reactive food if you show no signs of an allergic reaction to it.

Oral allergy syndrome is a type of
cross-reactivity. With this syndrome, people who have pollen allergies (such as a
grass allergy) may develop itching, redness, and swelling of the lips and mouth
when they eat fruits or vegetables that contain a protein that reacts with the
pollen. These symptoms usually resolve quickly and do not involve other parts
of the body.

Oral allergy syndrome usually involves a reaction to
fresh fruits and raw vegetables:

If you are allergic to ragweed, your mouth may itch when you eat melons, especially cantaloupe.

If you are allergic to birch pollen, you may react to apple peels.

A growing number of people, especially health care
workers, are discovering that they have an allergy to
latex. Latex is the natural sap of the rubber tree. It
is used in making surgical gloves, condoms, balloons, and other products. If
you have a latex allergy, you may also have allergies to bananas, avocados,
kiwi, and chestnuts.

Other concerns

Some people have allergic reactions to food after they exercise. This is called exercise-induced food allergy. As a person's body temperature rises with exercise, symptoms such as itching and lightheadedness start, sometimes leading to hives and even anaphylaxis, which can be deadly. To avoid exercise-induced food allergy, do not eat for a few hours before you exercise or right after exercising.

Symptoms

Symptoms of
food allergy can affect many parts of your body,
including your:

Digestive system. Symptoms include stomach cramps,
nausea, vomiting, diarrhea, itching in the mouth and throat, and rectal
bleeding (rare in adults). These symptoms occur more often in children
than in adults.

Skin. Symptoms include
hives or welts, swelling, itching, redness, and atopic dermatitis. Skin reactions are common in
children.

Children usually have the same symptoms as adults.
Symptoms of milk or soy allergies in children may include
eczema. Sometimes the
only symptoms are extreme crying,
vomiting, blood in the stool, diarrhea, constipation, or poor growth.

Symptoms vary from mild to life-threatening and can appear
from within minutes to days of eating a food. The most severe reaction is
anaphylaxis, which affects many body systems and can be deadly.

Anaphylaxis can start within a few minutes to a few hours after you eat the
food. And the symptoms can go away and come back hours later. Common triggers for anaphylaxis are peanuts, nuts,
and seafood. In children, peanuts cause anaphylaxis more often than other
foods. Aspirin, exercise,
or alcohol can increase the risk for anaphylaxis.

What Happens

The first time you eat a food
that triggers an
allergic reaction, your body's immune system
recognizes the food as a foreign substance (allergen). Your
body reacts by developing
antibodies against the food. When you eat the
offending food again, the antibodies attack the allergen, releasing histamine
and other chemicals that cause the symptoms of an allergic reaction.

What Increases Your Risk

Have a family history of allergy. If both of your parents have allergies, you are more likely to have allergies.

Have another allergic condition such as
atopic dermatitis or
asthma.

Are young. Infants and children
have more food allergies than adults.

Have a medical condition that
makes it easier for
allergens to pass through the walls of the stomach and
intestines and enter the bloodstream. These conditions include gastrointestinal
disease, malnutrition, prematurity, and diseases that
impair the immune system, such as eosinophilic esophagitis (EoE).

You have a greater risk for a life-threatening allergic
reaction (anaphylaxis) from food allergy if you:

Have
asthma.

Develop allergy symptoms within
minutes of eating the food.

If you or your child has a severe food allergy, always
carry an
allergy kit and know how to use it. You should also
wear a medical alert bracelet at all times. Being prepared to immediately deal
with a severe allergic reaction reduces the risk of death.

When To Call a Doctor

Call 911 or other emergency services immediately if you have had a severe reaction in the
past from the same food and similar symptoms are developing. If you have an
allergy kit prescribed by your doctor for severe
allergic reactions, give yourself the
epinephrine shot before you call for help. If
possible, have someone else call while you give yourself the shot.

Because symptoms can come back even after the injection, go to the
emergency room every time you have a reaction, even if you are feeling better.
You should be observed for several hours after the reaction.

Call 911 or other emergency services immediately if you have any of the following
symptoms:

A nutritionist or
registered dietitian can help you keep a balanced diet
even when you can't eat some foods. A nutritionist or dietitian can also help
you learn how to avoid hidden
allergens in foods and give you ideas about how to
make substitutions in recipes.

Exams and Tests

To diagnose a
food allergy, your doctor will start with a
medical history and a physical exam. Your doctor may
ask:

What symptoms you have.

If your family has any food allergies.

How soon the symptoms began after eating food.

If over-the-counter medicines helped.

If other people also got sick.

How the food was prepared.

If you ate any other foods.

It's important to find out whether you have a
food allergy or food intolerance. Your doctor may ask you to keep a record of
all the foods you eat and any reactions you have to them. Your doctor will also consider if your reaction could have been caused by things like allergies to medicines or insect stings, food poisoning, irritants in foods, or exposure to skin irritants.

Your doctor may ask you
to try an elimination diet, an oral food allergy challenge, or both.

In an elimination diet, you avoid eating foods that may be causing an allergic reaction and see if your symptoms go away. If symptoms come back when you eat the food again, your doctor can confirm your food allergy. The elimination diet can last from 2 to 8 weeks.

In an oral food allergy challenge, you eat a variety of foods that may or may not cause an allergic reaction. Your doctor
watches to see if and when a reaction occurs. This test
is considered the best way to diagnose a food allergy.

After you have been diagnosed with a food allergy, you may also have
allergy tests, such as skin tests or blood tests, to find out which foods you are allergic to.

Treatment Overview

The best treatment for
food allergies is to avoid the food that causes the
allergy. When that isn't possible, you can use medicines such as
antihistamines for mild reactions and the medicines in
an allergy kit for serious reactions.

Start by telling your family, friends, and coworkers that you
have a food allergy, and ask them to help you avoid the food. Read all food
labels, and learn the
other names that may be used for food
allergens.

If your baby has a milk or soy allergy, your
doctor may suggest either that you change the formula or that you feed your baby only breast milk.
Specially prepared formulas are available for infants who have soy and milk
allergies.

If you or your child has mild allergies,
your doctor may suggest nonprescription
antihistamines to control the symptoms. You may need
prescription antihistamines if over-the-counter medicines don't help or if
they cause side effects, such as drowsiness.

If you
have a severe allergic reaction, your first treatment
may be done in an emergency room or by emergency personnel. You will be given a
shot of
epinephrine to stop the further release of histamine
and to relax the muscles that help you breathe.

How to treat a reaction

If your doctor has prescribed an
allergy kit, always keep it with you. It contains a
syringe of
epinephrine and
an antihistamine. It's important to give the epinephrine shot right away. Your doctor or pharmacist will teach you how to give yourself a shot. Be sure to check the expiration
dates on the medicines, and replace the medicines as needed.

You should also wear a medical alert bracelet or other jewelry that lists your food allergies. You can order
medical alert jewelry through most drugstores or on the Internet.

Children and food allergies

It's
important to take special care with children who have food allergies. A child
with severe food allergies may have a life-threatening
anaphylactic reaction to even a tiny amount of a food
allergen. Your child should always wear a medical
alert bracelet and carry an allergy kit.

Make sure that all caregivers (school
administrators, teachers, friends, coaches, and babysitters):

Know about your child's food
allergy.

Can recognize the symptoms of a food
allergy.

Know where the allergy kit is kept and how to give the
epinephrine shot.

Know to call
911 immediately.

Children may have only mild symptoms in the first few
minutes after they eat the food allergen, but they may have severe symptoms in
10 to 60 minutes. Children always should be observed in a hospital for several
hours after a reaction.

Always carries an allergy kit. Children at risk of severe allergic reactions should keep the kits at school or day care and at home. Older, mature children should be taught to give themselves the shot.

Although your child needs to avoid certain foods, he or she still needs to eat healthy foods. A dietitian can tell you which foods are important for your child's health.

Prevention

Food allergies
often occur in people who have a family history of asthma,
atopic dermatitis, or allergies to pollen, mold, or
other substances. These people are said to be
atopic, meaning they have an inherited tendency to
have allergic conditions. Allergies cannot be prevented in these people.

There isn't enough proof to recommend that people who are at risk for allergies should avoid common foods that cause allergies or foods that may be similar to common allergens like milk, eggs, peanuts, tree nuts, soy, wheat, fish, and shellfish.

If you are a
woman with a food allergy who is planning on a pregnancy and breast-feeding,
talk to your doctor about what foods to avoid while pregnant or nursing. But if you don't have food allergies, avoiding certain foods during your pregnancy isn't recommended as a way to prevent the baby from having food allergies.

The American Academy of Pediatrics recommends that all babies be
breast-fed for the first year of life or longer.1 For
babies with family members who have food allergies, breast-feeding only for at
least 4 months may help prevent allergies to milk.2 If
your baby is at high risk for allergies and you can't breast-feed, try a
hydrolyzed milk formula. The milk protein in hydrolyzed formulas is changed to
try to prevent allergies. There is no proof that giving your baby soy formula instead of cow's milk formula will prevent a food allergy in children at risk for food allergies.2

Tobacco smoke can make allergies worse, so it is important to have a smoke-free
environment.

Home Treatment

Knowing which foods trigger
food allergies and avoiding those foods is the best
way to prevent
allergic reactions. Unfortunately, food allergens are
often hidden in sauces, ice creams, baked goods, and other items.

If you have
food allergies, read food labels carefully. Be aware of
other names for food allergens, such as "caseinate" for milk or "albumin" for
eggs. Many people think that seeing "nondairy" on a label means there is no
milk in the product. This is not necessarily true.

Sometimes
products are recalled when food ingredients are missing from food labels. For a
list of recalled products, see the U.S. Food and Drug Administration's Recalls,
Market Withdrawals, and Safety Alerts page at
www.fda.gov/opacom/7alerts.html.

Tips for eating out

Eating out can be dangerous for
people with severe food allergies.

Bring safe substitutes from home. For example,
bring soy milk to have with cereal.

Be aware of possible
cross-contamination. For example, an ice cream scoop may have been used for
Rocky Road ice cream, which contains peanuts, and then used for your vanilla
ice cream.

Alert the wait staff to the possibility of a severe food
reaction. Carefully question them about ingredients. If they are not sure, ask
to speak to kitchen staff.

Always wear
medical alert jewelry that lists your food allergies. Medical alert jewelry can
be ordered through most drugstores or on the Internet.

If you or your child has ever had a severe allergic reaction, always carry an
allergy kit that contains a syringe of epinephrine and an antihistamine.

If you are traveling to another country, learn the words
for the foods that trigger your allergy so that you can ask in restaurants and
read food labels. Call airlines, tour operators, and restaurants ahead of time
to explain your food allergy and request safe meals. Prepare your own food when
possible. Discuss your travel plans with your doctor.

Medications

Medicine is used to treat some
food allergies. Medicines to treat a severe allergic
reaction or an
anaphylactic reaction are packaged in a prescribed
allergy kit.

For mild allergic
reactions, people often try nonprescription medicines first. You can try
prescription medicines if over-the-counter medicines fail to control allergy
symptoms or if they cause drowsiness or other bothersome side effects.

Medicine choices

Medicines used to treat a severe
allergic reaction include:

Epinephrine.
Epinephrine is given as a shot. It acts quickly to relax the muscles that help you breathe. Sometimes more than one shot is needed if symptoms do not go away. Epinephrine is the medicine used to prevent anaphylaxis.

Antihistamines. Antihistamines block the action of
histamine during an allergic reaction and help improve symptoms such as itching
and sneezing.

Antihistamines and corticosteroids for hives,
gastrointestinal symptoms, or sneezing and a runny nose.

Bronchodilators for
asthma symptoms. Bronchodilators relax the airways of
the lungs, making it easier to breathe.

Other Places To Get Help

Organizations

American Academy of Allergy, Asthma, and
Immunology

555 East Wells Street

Suite 1100

Milwaukee, WI 53202-3823

Phone:

(414) 272-6071

Email:

info@aaaai.org

Web Address:

www.aaaai.org

The American Academy of Allergy, Asthma, and Immunology
publishes an excellent series of pamphlets on allergies, asthma, and related
information. It also provides physician referrals.

American College of Allergy, Asthma, and Immunology
(ACAAI)

85 West Algonquin Road

Suite 550

Arlington Heights, IL 60005

Phone:

1-800-842-7777 (allergist referral service)

Email:

mail@acaai.org

Web Address:

www.acaai.org

The American College of Allergy, Asthma, and Immunology
(ACAAI) provides allergy information for consumers, including a nationwide
allergist referral service.

Asthma and Allergy Foundation of America
(AAFA)

1233 20th Street NW

Suite 402

Washington, DC 20036

Phone:

1-800-7-ASTHMA (1-800-727-8462)

Email:

info@aafa.org

Web Address:

www.aafa.org

The Asthma and Allergy Foundation of America (AAFA)
provides information and support for people who have allergies or asthma. The
AAFA has local chapters and support groups. And its Web site has online
resources, such as fact sheets, brochures, and newsletters, both free and for
purchase.

Food Allergy and Anaphylaxis Network

11781 Lee Jackson Hwy

Suite 160

Fairfax, VA 22033-3309

Phone:

1-800-929-4040

Fax:

(703) 691-2713

Email:

faan@foodallergy.org

Web Address:

www.foodallergy.org

The Food Allergy and Anaphylaxis Network (FAAN) publishes several
newsletters and dozens of books, booklets, and videos designed to educate
people about food allergies. The nonprofit organization also works on federal,
state, and local initiatives in such areas as food labeling, schools, emergency
medical services, camps, restaurants, and airlines. The FAAN Web site includes
links to children's and teenagers' food allergy Web sites.

National Institute of Allergy and Infectious Diseases
(NIAID), National Institutes of Health

NIAID Office of Communications and Government Relations

6610 Rockledge Drive, MSC 6612

Bethesda, MD 20892-6612

Phone:

1-866-284-4107 toll-free

Phone:

(301) 496-5717

Fax:

(301) 402-3573

TDD:

1-800-877-8339

Web Address:

www.niaid.nih.gov

The National Institute of Allergy and Infectious
Diseases conducts research and provides consumer information on infectious and
immune-system-related diseases.

Related Information

References

Citations

American Academy of Pediatrics (2012). Policy statement: Breastfeeding and the use of human milk. Pediatrics, 129(3): e827–e841. Also available online: http://pediatrics.aappublications.org/content/129/3/e827.full.

Greer FR, et al. (2008). Effects of early nutritional
interventions on the development of atopic disease in infants and children: The
role of maternal dietary restriction, breastfeeding, timing of introduction of
complementary foods, and hydrolyzed formulas. Pediatrics, 121(1): 183–191. Also available online: http://pediatrics.aappublications.org/content/121/1/183.full.

Other Works Consulted

Food Allergy and Anaphylaxis Network (2010). How to read a label. Available online: http://www.foodallergy.org/files/media/downloads/HTRLsheet2010.pdf.

American Academy of Allergy, Asthma, and Immunology (2010). Guidelines for the diagnosis and management of food allergy in the United States: Report of the NIAID-sponsored expert panel. Journal of Allergy and Clinical Immunology, 126(6): S1–S58. Available online: http://www.niaid.nih.gov/topics/foodallergy/clinical/Pages/default.aspx.

American Academy of Pediatrics (2012). Policy statement: Breastfeeding and the use of human milk. Pediatrics, 129(3): e827–e841. Also available online: http://pediatrics.aappublications.org/content/129/3/e827.full.

Greer FR, et al. (2008). Effects of early nutritional
interventions on the development of atopic disease in infants and children: The
role of maternal dietary restriction, breastfeeding, timing of introduction of
complementary foods, and hydrolyzed formulas. Pediatrics, 121(1): 183–191. Also available online: http://pediatrics.aappublications.org/content/121/1/183.full.

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